
What I'm getting is that a downdraft is associated with rain.
Our normal puffy white cumulus (if I'm understanding this correctly) actually has an updraft immediately in front, which causes a net REDUCTION in wind speed and a header! This is the thermal effect, and the resulting subsidence will create a lift and increased speed along the side of the cloud. This is if and only if, the cloud is low enough to interact with the boundary layer.
If you look at the cumulus and it has a wispy base, that is a sign the cloud is not interacting with the boundary layer.
But, I'm getting a little confused...
The picture I have in my head is my last trip to Wildcat.